A stem for a semiconductor laser device of a terraced substrate structure which has a tilted active layer against flat parts of the substrate, the stem comprises a base plate and a heat sink block, a flat face of the heat sink block for bonding the semiconductor laser device thereonto is tilted with respect to a base face of the base plate; this stem has features that the polarization direction of the lased light from the semiconductor laser device can be set to be parallel to (or perpendicular to) the base face of the base plate, and therefore it becomes much easier to make adjustments related with the polarization direction of the lased light.